1. Field of the Invention
The present invention relates to a gear synchronizer assembly for power transmissions, and more particularly, but not exclusively, to a gear synchronizer assembly of the type which comprises a gear member rotatable on a transmission shaft, a spline piece mounted on a hub portion of the gear member for rotation therewith and being formed at one side thereof with a conical portion and thereon with external spline teeth, a synchronizer ring mounted on the conical portion of the spline piece for frictional engagement therewith, a hub member fixedly mounted on the transmission shaft for rotation therewith and being formed thereon with external spline teeth, a clutch sleeve encircling the hub member and having internal spline teeth in continual engagement with the external spline teeth of the hub member, the clutch sleeve being axially shiftable to be engaged at the internal spline teeth thereof with the external spline teeth of the spline piece, and thrust means for thrusting the synchronizer ring toward the gear member in shifting operation of the clutch sleeve to effect frictional engagement between the synchronizer ring and the spline piece.
2. Discussion of the Background
In such a conventional gear synchronizer assembly as described above, the thrust means comprises a plurality of circumferentially spaced strut keys each having a raised portion in engagement with the corresponding recess in the inner peripheral wall of the clutch sleeve, and an annular retainer spring arranged to bias the strut keys radially outwardly for engagement with the clutch sleeve. To simplify the thrust means in construction, there has been proposed an improved thrust means wherein the strut keys and retainer spring are replaced with a single thrust element. It is, however, difficult to enhance productivity of the gear synchronizer assembly because the single thrust element is complicated in configuration and construction.
To overcome the shortcomings of such a conventional thrust means as described above, an improved gear synchronizer assembly has been proposed by Ikemoto et al. in U S. Pat. No. 4,625,844, issued on Dec. 2, 1986, wherein the clutch sleeve is formed at its inner periphery with at least one internal radial projection, and wherein the thrust means comprises a radially contractible annular resilient member supported in place by engagement with the inner circumference of an outer cylindrical hub portion of the hub member, the annular resilient member having an axial leg extending therefrom toward the internal radial projection of the clutch sleeve and having a radial projection arranged to be brought into engagement with the internal radial projection of the clutch sleeve and arranged to abut against and urge the synchronizer ring toward the spline piece upon engagement with the internal radial projection of the clutch sleeve, the axial leg of the annular resilient member being arranged to be compressed radially inwardly by engagement with the internal radial projection of the clutch sleeve.
In the above-described synchronizer assembly, it is required to accurately position the axial leg of the annular resilient member for engagement with the internal radial projection of the clutch sleeve so as to ensure reliable operation of the synchronizer assembly. In the process of assembly of the synchronizer assembly, however, there is a fear that the axial leg of the annular resilient member may not be arranged in a proper position. Additionally, if the axial leg of the annular resilient member is vibrated by an impact acting thereon during travel of the vehicle, it will be displaced from its proper position.